This invention relates generally to filaments, and more particularly relates to the design and fabrication of submicron scale filaments formed of microfabrication materials such as metallic and semiconducting materials.
Interest in the production of metal and semiconductor filaments, and filaments of microfabrication materials in general, of submicron dimensions, is rapidly growing as applications in, e.g., mesoscopic physics and nanoscale systems, proliferate. Metal and semiconductor filaments provide an ability to integrate electrical interconnects and functional elements into electronic, optoelectronic, and electromechanical devices and systems in the submicron and nano-scale regimes. A wide range of MEMS and nano-scale systems cannot be fully realized without integration of such filament elements in the systems.
Historically it has been quite challenging to synthesize metal and semiconductor filaments with a high degree of control over filament morphology and dimensions. Solution-phase, vapor-phase, and vapor-liquid-solid (VLS) filament growth techniques, among others, have all been proposed. In particular, VLS filament growth has emerged as an important method for the fabrication of high-quality semiconductor filaments. But semiconductor filaments produced by processes such as conventional VLS growth are inherently limited to micrometer-length scales, are characterized by extreme mechanical fragility, and lack global orientation.
One application for metal and semiconductor filaments, namely, integration in optical fibers, cannot generally be realized by conventional VLS or other such growth techniques. Several attempts have been made to embed submicron filaments into optical fibers with methods such as high-pressure chemical vapor deposition, pumping-and-filling techniques, and multiple-step, draw-cut-stack methods. But the orders-of-magnitude disparity between typical fiber dimensions and filament dimensions has posed severe challenges to the successful implementation of these techniques.